Technologies

What Our Customers Are Saying

Our relationship with Reverse Polarity LLC has been nothing short of amazing. They joined our team during a difficult transition phase yet made the process seamless, from helping with support issues to identifying short and long-term needs. In just a few weeks, they developed a cost effective and balanced strategic plan, utilizing Open-Source software solutions, that will meet the needs of our school today and for years to come. I could not be happier with the services and solutions they offer, and having them involved in our IT decisions makes me feel safer and more secure about our network.

Preparing The Hard Drives:

Overwriting the drives with random data
In order to be sure that your data is securely protected, the first step in preparing each drive requires that we overwrite the entire drive with random data. This will ensure that it will be (nearly) impossible for someone to determine where your encrypted data begins and where it ends, making it much more difficult for them to mount a cryptographic attack on your drives to gain access to your data.

On Linux (or any *nix system) there exists a simple but useful tool called dd. dd has several uses, but we will be using it to overwrite each of the removable hard drives with random data from /dev/urandom.

The first step is to plug in a new drive and then determine what block device node your system assigns to it. To find out, run dmesg after plugging the drive in. You should then see something similar to this at the end of the dmesg output:

The bolded text in the dmesg output above shows that when the Seagate ST3750528AS 750GB SATA drive was plugged into an eSATA dock, udev assigned it a block device node of /dev/sde. Your drive may be assigned a different node and you need to be 100% sure that you identify the correct drive because the next command will completely overwrite the entire contents of the drive, including the partition table.

As root, be sure to substitute sde with the correct device indicated by dmesg on your system and run the following command:

root@host: # dd if=/dev/urandom of=/dev/sde bs=1M

Repeat these two steps (dmesg & dd) for each of the remaining drives.

*IMPORTANT* Depending on the size of the hard drive and the speed of the system, this operation will take hours or even days. Be patient. To ensure that your encrypted hard drives are as secure as possible against a cryptographic attack, you must allow this process to finish on each drive.

If you are impatient, or just want to know how far along the process is, you can keep track of the process in another shell by typing the following command:

root@host: # while true; do killall -USR1 dd; sleep 1; done

This will send a USR1 signal to the running dd command every second, causing the running dd command to display it's progress like so: